1. Field of the Invention
The present invention relates to a video camera (a VTR provided with a camera) for recording an object captured by the camera.
2. Description of Related Art
FIG. 1 is a block diagram showing an essential configuration of a prior art video camera disclosed in Japanese Patent Unexamined Publication No.4-90273. A power switch 24 used to cut off power is connected to a power supply circuit 25. Supplied to a power cutoff circuit 27 are: a contact detection signal 32 from a contact detection circuit 31 that detects the opening, after the closure, of a contact switch provided on the grip of the video camera; a swing detection signal 29 from a swing detection circuit 30 that detects a swinging motion of the video camera; and a record ON signal 28 that is output during a recording operation. The power cutoff circuit 27 outputs a power cutoff signal 26 which is supplied to the power supply circuit 25.
The operation of the above video camera will be described below. When the contact switch provided on the grip of the video camera is closed by the pressure of the hand holding the grip, the contact detection circuit 31 does not output the contact detection signal 32. The contact detection signal 32 is output and supplied to the power cutoff circuit 27 when the pressure is released from the contact switch. The swing detection circuit 30 detects a swinging motion of the video camera by means of an angular velocity sensor (not shown) built in the video camera, and upon detection of the swinging motion, supplies the swing detection signal 29 to the power cutoff circuit 27. The video camera has a construction such as shown in FIG. 2. When an operator is carrying the video camera VC by gripping a handle H in his hand, the video camera VC is lightly swung back and forth as he walks. This swinging motion is detected by the angular velocity sensor built in the video camera. When the video camera is in a recording operation, the record ON signal 28 that signifies that the video camera is recording is supplied to the power cutoff circuit 27. While the recording ON signal 28 is being supplied to the power cutoff circuit 27, if the application of the swing detection signal 29 continues for a predetermined length of time (for example, one minute), the power cutoff signal 26 is supplied to the power supply circuit 25 to cut off the power of the video camera VC.
In recent years, video cameras have been drastically reduced both in size and weight, and video cameras without such a carrying handle as shown in FIG. 2 are a general trend. Furthermore, video cameras generally known as single-hand video movie cameras are so designed that, when not photographing, the operator carries the video camera with his hand placed on the grip which is usually used to hold the camera during photographing, or the video camera is carried in a shoulder bag or the like or on a shoulder strap attached to the camera.
Thus, as the video camera becomes smaller and lighter, the method of carrying it has been changing. Since the video cameras that can be carried with the operator's hand placed on the grip are not provided with a carrying handle, no such signal as supplied from the contact detection circuit described above can be obtained to cut off power when the video camera is being carried. Furthermore, when the video camera is carried in a shoulder bag or the like, the swinging directions of the video camera are not determined, and the amount of its swinging movement is usually smaller than when it is carried with its grip held by hand, so that the level of the output signal of the angular velocity sensor becomes smaller. When it is carried on a shoulder strap, the swinging directions of the video camera are not determined, as in the above case; therefore, it is difficult to judge whether the video camera is being operated for photographing a scene or is just being carried. Accordingly, recent video cameras without a carrying handle have the problem that when the camera is carried around while being mistakenly left in a record mode, the recording operation is allowed to continue, and misrecording cannot be prevented. Another problem is that if the video camera is subjected to heavy shaking while photographing a scene, thus adversely affecting the quality of the captured image, the operator may not notice the adverse photographing condition and may continue the photographing operation as he is so absorbed in photographing the scene. There is the further problem that once misrecording is done, the misrecorded portions remain recorded on tape, which, when replayed, reproduces misrecorded, jarring images here and there.